Answers About Old Gas Sites Repurposed as Injection Wells for Fracking’s Toxic Wastewater May Never Be Fully Unearthed

A little over a month after Penneco Environmental Solutions received approval in May 2021 from the Environmental Protection Agency to dispose of an additional 2.16 million gallons of highly toxic fracking wastewater in its disposal well in Plum Borough, Pennsylvania, a pressure valve tripped and shut down the well.

Penneco, which had submitted well schematics detailing the condition of the well’s materials as part of its permit application process with the EPA, investigated and told the agency “either the weight or the quality” of a seven-inch cement casing around the well was inadequate. The company installed a new casing.

About a month after Penneco replaced the well casing, the state Department of Environmental Protection (DEP) received a “residential water supply complaint” from Katie Sheehan, a Plum resident, who said the spring near her home, which is down the hill from Penneco’s site, had suddenly developed “a funny taste and smell to it.” The spring is “the main source of water for my parents’ house,” Sheehan said. When the DEP followed up with Penneco 11 days later, the company said it had notified the EPA of the complaint.

Penneco was subsequently issued a “notice of violation” by the DEP for failing to report the leak to them within 24 hours, even though the agency’s testing later concluded no water contamination had occurred as a result of the leak.

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Now, with the EPA having approved a new permit last month for another Penneco disposal well in Plum Borough, known as “Sedat 4A,” residents of the rural community outside Pittsburgh and their consultants say that the environmental costs and risks of a second well far outweigh any potential benefits of increased toxic waste disposal. 

Penneco’s existing disposal well in Plum, “Sedat 3A,” is a repurposed conventional gas well; Sedat 4A is near the end of its life as a conventional gas well, and would be repurposed for injection if issued a permit. The wells were originally drilled in the 1980s and early 2000s, respectively, and neither was initially designed to hold millions of gallons of highly toxic wastewater at high pressure.

“If you’re risking using an old well for many decades to come, it’s going to be repressurized many times at pressures higher than it ever saw as a gas well,” said Tony Ingraffea, a professor emeritus of engineering at Cornell University who is advising an organization opposed to the repurposing of the well.

“Spend the money upfront before you make a mistake. And they didn’t,” Ingraffea said of Penneco’s Sedat 3A.

Ingraffea added that state and federal environmental regulators have no clear definition of what “forever” means when it comes to storing the wastewater, which contains proprietary chemical concoctions, is typically far saltier than ocean water, and is laced with benzene, arsenic and radium 226 and 228, both radioactive isotopes, as well as other toxic chemicals.  

Matt Cwiklik, a former solid waste inspector with the DEP who now writes advocacy letters on behalf of Protect PT, a local environmental group, said the fact that Penneco “is still moving forward with the same operation at the same site is a little baffling.” 

Protesters outside a natural gas convention in Pittsburgh. Credit: Scott Goldsmith
Protesters outside a natural gas convention in Pittsburgh. Credit: Scott Goldsmith

After the EPA’s decision to issue the project a permit, the only bureaucratic hurdles Penneco must clear are at the state level. “The ball is now in the DEP’s court,” said Cwiklik, as the agency is evaluating Penneco’s application for a waste-transfer, and a well permit. 

Ben Wallace, chief operating officer at Penneco, responded that a conventional well stores waste that the EPA classifies as “residual,” not “hazardous.” 

“There are certain things that come out of the earth that are not good for people,” he said. “I agree that you shouldn’t drink these things and that these fluids are not compatible with humans. But they already live in the earth and we’re putting them back in.” Wallace also said that, so far, radiation readings from trucks delivering produced water to the Sedat site have never exceeded radiation levels in the environment aboveground. “Frankly, that’s surprised us,” he said.

And repurposing a conventional well for injection is common industry practice, Wallace said. “The thing about drilling a new well is that you don’t know exactly what you’re going to drill into in the formation until you drill it,” he said. “When you have an existing well, you already have access to that data. You’re injecting into a known entity and can much better quantify the zone of injection.”

The EPA has expressed confidence in Penneco’s proposed conversion process for Sedat 4A, the suitability of the formation for injection and the low likelihood of seismicity in the area.  

Lauren Carmarda, the DEP’s communications manager for the southwest region, said via email that the agency is currently in the process of conducting a “thorough and detailed review” of all the materials Penneco submitted as part of its application. Because of this, “we can’t answer your questions or comment on specifics at this time,” she said.

Over time, Pennsylvania’s conventional wells have dried up and been abandoned as unconventional, or fracked, wells have become favored for their ability to penetrate deeper into shale formations.

According to data oil and gas companies report to the DEP, the fracking industry generated about 2.6 billion gallons of liquid waste—known as produced water—from oil and gas projects in Pennsylvania in 2022. Most of this gets recycled and used to frack additional wells. But given its toxic composition, produced water can only be reused a finite number of times. 

As produced water is treated, reused, cleaned to some degree and reused again, Ingraffea said, it becomes increasingly impure, making it less effective in the fracking process. Inevitably, it must be disposed of somewhere. 

The oil and gas industry’s preferred disposal method is injection. There are hundreds of thousands of injection wells across the country, the majority of which have operated without detected incidents. But Pennsylvania does not have robust injection well infrastructure; instead the state has historically relied on 200-plus injection wells in Ohio to dispose of its billions of gallons of produced water each year. 

As pressure from residents and environmentalists in Ohio has increased scrutiny over the practice, companies in Pennsylvania have begun eyeing conversion of conventional wells in the state for wastewater disposal. 

The Importance of Testing

All the pressurizing and depressurizing necessary to inject liquid waste from oil and gas operations into a converted injection well stresses its “wellbore integrity,” said Ingraffea, “a fancy word for the well should only be used for what it’s designed to do and nothing more.” 

“We’re starting with a well that has been underground for decades,” he said. “Some degradation had to occur.”

One of the ways to test for degradation, said Ingraffea, is to conduct an expensive and time-consuming test called a “cement bond log.” In practice, it is complex, but Ingraffea said it is simple enough to model using your hand and a wine glass. 

“Hold the wineglass by the stem and bang on the wine glass with a spoon. You now have a bell ringing, right? And it reverberates at a high pitch,” he began. “Now, put your hand around that wineglass and bang it with a spoon. What do you hear? Thud. It won’t have that high pitch reverberation.” 

This is an approximation of how  cement bonds of wells are tested: a company lowers a device emitting sound waves into the steel casing of the well, which, in turn, causes the steel to vibrate. If the casing makes high pitched sounds, the cement bonding has uncoupled from the shaft, like the wine glass absent a cupped hand.

Ideally this whole operation is conducted using state-of-the-art equipment, but when Ingraffea reviewed Penneco’s cement bond logs for its first well, Sedat 3A, he said he found them cursory. The company used “the simplest, cheapest kind of cement bond log,” said Ingraffea, instead of what he called “state of the art” technology, which would have involved exciting the steel with ultrasonic sound waves. 

When asked if Penneco used ultrasonic equipment to conduct its cement bond log for Sedat 3A, Wallace said the company hired Surefire Wireline, an oil and gas well surveying company, which  conducted “Gamma Ray & Acoustic Cement Bond logs.” Those are “standard industry practice,” said Wallace. Before  Penneco brings Sedat 4A online, it will install a new casing and submit a cement bond log of that and the other casings in Sedat 4A to the EPA and DEP, as the company is required to do. 

In its response to public comments about the proposed well’s environmental risks, the EPA said that, under the permit it approved, Sedat 4A could not start operating until Penneco completes conversion and conducts an initial test to “demonstrate the mechanical integrity of the injection well.” 

The EPA did not say whether it would evaluate that test with increased scrutiny, given the incident involving Sedat 3A’s casing.

Whatever level of scrutiny is applied, Sheehan, who first complained to the DEP about water quality issues, believes the environment near her home has been harmed, even if Sedat 3A did not damage her water, as DEP later concluded. 

“I feel like there could be an endangered beetle living in that area and there would be more concern for that beetle with environmental protection and policies going in place,” she said, “and more people in an uproar than there is for human life.” 

“Nothing Goes Forever”

Cwiklik, who co-authored a citizens’ comment to the DEP addressing some of the community’s concerns with the repurposed well, is troubled by the apparent regulatory consensus about what happens to produced water stored in an injection well. “It is just, you know, assumed that nothing will ever happen,” he said. “There isn’t any post-closure monitoring.” 

Penneco has one injection-monitoring well onsite, Sedat 1A, an old gas well that now monitors well 3A; the company has proposed using the abandoned Sedat 2A to monitor well 4A. As part of his comment-writing process, Cwiklik reviewed the environmental assessment Penneco submitted to the DEP, and noticed that the topography of the well site may render those monitoring wells ineffective. 

“Surface topography is always irrelevant when you’re dealing with subsurface structure,” said Penneco’s Wallace, who added that converting old wells to monitor Sedat 3A and 4A was not required to receive a permit from the EPA. It “is a feature you can develop for additional safety,” he said.

Unless it’s under high amounts of pressure, “water flows downhill. It flows downhill on the surface and in the subsurface,” said Sue Brantley, a geologist at Penn State who studies the relationships between oil and gas waste and the underground environment. “If there is a problem, you probably want your monitoring well to be down flow,” she said. 

Produced water migrating deep below ground is rare but not impossible, said Brantley. “In general, a well managed, well designed, deep injection well is really safe,” she said, but added that, sometimes, “there are problems.” 

Geological formations with enough subsurface porosity to hold large volumes of liquid, such as produced water, are often the same ones that held oil and gas before the fossil fuel industry extracted it.

This is exactly the type of formation Penneco believes it is injecting into. “We have this Murrysville formation that’s a very brittle, very porous sandstone that’s a capable receiving formation,” with “confining layers” of dense rock above and below it to prevent water migration, Wallace said.

The EPA appears to agree. “The Murrysville Formation in the area of the #4A well has produced natural gas and this opens up pore space within the formation to store the injected fluid,” making the proposed site suitable for pumping in produced water, the agency said in its response to public comments.

But problems can arise if fractures begin to develop in the Murrysville Formation—a potential byproduct of repeat injections. These small openings could allow produced water to migrate underground “really, really slowly,” because it would be moving between “high pressure in one place and lower pressure somewhere else,” Brantley said. “Even the pretty small pressure difference—if you’re a geologist and you think over long time periods—the water in the subsurface is going to move.” 

The company would be permitted by the EPA to inject 2.16 million gallons of produced water a month into Sedat 4A. “Limiting both the volume of the fluids injected and the injection rate,” as the EPA has required of Penneco, “checks the potential for seismicity,” the agency wrote in its response to public comments. 

But movement isn’t the only danger. In some places in the U.S., like Oklahoma and Ohio, Brantley said, pumping too much produced water down a well too fast is “when earthquakes happen.” 

The EPA believes that’s unlikely with these particular wells. While the agency is not legally obligated to assess seismicity risks when permitting an injection well, in granting its permit to Penneco it characterized the probability of intense seismic activity in southwest Pennsylvania as low. 

Brantley was grateful the EPA took the time to address seismicity, but found the agency’s assessment of seismic risk limited in its scope. There may be “plenty of faults closer to home,” than the ones the EPA had identified 2,000 miles to the east, she said. “We don’t know where they all are.”

In its response to public comments, the EPA characterized the Murrysville formation as thick, porous and permeable, making it “suitable for gas and liquid storage or disposal.” David Sternberg, a spokesperson for the agency, said in an email that in the EPA’s history of permitting injection wells in and near Pennsylvania, there has never been a “known induced seismic event or endangerment to an underground source of drinking water” from an injection well.

“We don’t believe there is any seismic risk,” with Sedat 4A, said Penneco’s Wallace, who acknowledges that seismicity is a concern for the industry in other areas of the country.

Brantley stressed that the rate at which produced water may migrate underground was incredibly slow, and that Penneco’s proposal to inject into a porous reservoir that’s been depleted of most of its gas is “state of the art.” 

Handling produced water when it’s above ground, she said, is riskier than disposing of it in an injection well. But, she said she was not prepared to say a properly constructed injection well would keep produced water below ground indefinitely. “From a geologist’s point of view, nothing goes forever,” she said. “We cannot always predict what is going to happen.”

Pennsylvania’s Growing Number of Injection Wells

Sedat 4A would be Pennsylvania’s 15th injection well, and of the 14 preceding it, nine were permitted back in the 1980s, including Sedat 3A.

Uninterrupted expansion is not assured for the oil and gas industry in Pennsylvania. Both Sedat 3A and 4A have faced considerable community opposition, with Protect PT and Plum Borough officials still challenging Penneco’s new well proposal on zoning grounds before the Pennsylvania Commonwealth Court. 

Gillian Graber, Protect PT’s founder and executive director, has said it is also possible that the group could go to court to challenge the EPA permit. “All of this stuff is an uphill battle,” she said. “You may have what you think is the most solid case, but it’s still difficult to win because the case law is so squarely in favor of industry throughout our history in the state and in the country.” 

For residents of Plum Borough, living alongside an injection well can pose risks beyond water leaks. Matt Kelso, a Plum resident who works as manager of data and technology at FracTracker Alliance, a nonprofit that raises awareness about oil and gas operations, doesn’t support another injection well in his community. “These things cause problems for neighbors,” he said, “they just do.” 

When Sheehan and her husband decided to move back to Plum in 2021, they “put everything we had into fixing up my grandmother’s house, and that’s where we had planned to live,” she said. But now, she suspects that air pollution and truck traffic near her home have lowered its value. “If anybody does any type of research, I don’t know why they would want to buy my house,” she said. 

A waste water tank truck passes on the main street of Waynesburg, Pennsylvania. Credit: Mladen Antonov/AFP via Getty Images
A waste water tank truck passes on the main street of Waynesburg, Pennsylvania. Credit: Mladen Antonov/AFP via Getty Images

Kelso isn’t sure what the answer to disposal is, but believes that the oil and gas industry is not being honest about the risks involved with injection. “If you take away the means of disposing of that fluid, the industry has a really big problem on their hands,” he said. “Fundamentally, it’s a problem they can’t solve.”

Cwiklik shared a similar sentiment about the future of Pennsylvania’s disposal methods. The state still produces billions of gallons of liquid waste alone, and with recent scrutiny over injection wells in Ohio, it may soon need other options. 

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“I see the cumulative effect of this becoming the next legacy issue, for all of us—for the entire country,” he said. “If the main argument is economic savings for the industry, that falls flat for me. There should be robust monitoring of the groundwater. How we get there and get that done is a different story altogether.” 

A good start, he said, would be to send more resources to the DEP, so they can more closely monitor the production, handling and disposal of fracking waste.

Ingraffea, the retired Cornell engineering professor, was not prepared to write off injection wells completely for fracking waste. “If the companies involved and the regulatory authorities involved do their jobs well and honestly, then history has shown that underground injection of waste can be acceptable,” he said. 

But just because “sending something underground might be the cheapest thing to do,” doesn’t mean we can forget about it, he said. “It’s still down there.” 

Ingraffea said that the federal government and nuclear energy industry have agreed upon standards for waste disposal that define how long the waste must be contained safely underground. He’d like to see similar regulations adopted for the fracking industry, too. 

“We don’t have set standards for underground injection from oil and gas wells for what they mean by ‘forever,’” he said.

The result, said Ingraffea: ”Forever is left to the beholder.”

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